A free fall simulator is essentially a vertical wind tunnel in which an upward flow or column of air is generated with sufficient velocity to produce a dynamic pressure high enough to suspend a person against the force of gravity. This enables the user to experience all the effects of free fall in a controlled, safe environment. Accordingly, with a free fall simulator, a user can experience the aerodynamic forces and the effects of body movements during free fall without jumping from an aircraft. Free fall simulators have become more popular in recent years because of the significant benefits and cost savings associated with free fall training in a free fall simulator compared to conventional free fall training from an aircraft, and because of the desire of the general public to experience free fall without the dangers and risks associated with jumping from an aircraft. Accordingly, in addition to military and other sky diving training facilities, free fall simulators are being considered for recreation purposes at fairs, carnivals, or the like where they can be used by the general public for experiencing free fall.
A variety of free fall simulators are known in the prior art. Specifically, a free fall simulator installed at Ft. Bragg, North Carolina for the U.S. Army comprises a recirculating system in which a single fan above the flight chamber creates a vertical air stream in the flight chamber sufficient to support a user under free fall conditions. Air which passes through the flight chamber is then recirculated to the bottom of the flight chamber for reuse.
U.S. Pat. No. 5,209,702 issued to Rarenas discloses a free fall simulator with a single fan below the flight chamber for producing a stream of air in the flight chamber to support the user.
The Kitchen et al. U.S. Pat. No. 5,655,909 discloses a sky diving simulator in which a plurality of radially positioned fans at the bottom of the simulator provide the stream of air within the flight chamber sufficient to support the user.
The Jean St-Germain U.S. Pat. No. 4,457,509 also provides a single fan at the bottom of the flight chamber but with a recirculating feature in which the air stream, after passing through the flight chamber, is recirculated back to the fan.
The Macangus et al. U.S. Pat. No. 4,578,037 discloses a sky diving simulator in which three inlet fans are provided at the bottom of the simulator and thus below the flight chamber. These fans are positioned at the end of inclined ducts so that the air inlet flows at an inclined angle from the inlet to the bottom of the flight chamber.
The Kitchen et al. U.S. Pat. No. 5,083,110 discloses a vertical wind tunnel training device providing a plurality of fans positioned above the flight chamber for producing a vertical stream of air within the flight chamber. Kitchen also discloses a single fan at the lower end of the device for producing the vertical air stream in a recirculating structure.
Most if not all of the prior art free fall or sky diving simulators are effective for producing a vertical stream of air with sufficient velocity to support a user against the force of gravity. Few, however, have focused on noise reduction. In any free fall or sky diving simulator, significant noise is generated by the fan drive system, by the movement of air through the fan system, and by jet noise generated by the vertical air stream. These noise sources generate broad spectrum noise that can, without careful design considerations, have damaging effects on both human safety and the structural integrity of the simulator. Noise reduction or noise attenuation has become and is becoming of greater importance as free fall and sky diving simulators, which at one time were found primarily at military installations and more remote locations as training facilities for paratroopers, firefighters, sky divers, etc., are now being installed in more populated areas at or near shopping malls, amusement parks and the like for recreational use.
Accordingly, there is a need in the art to provide a free fall or sky diving simulator which provides improved noise attenuation.
A need also exists in the art for a free fall or sky diving simulator which provides an improved ingress/egress system which permits users to enter and exit the flight chamber or an area adjacent to the flight chamber while maintaining adequate air flow and pressure within the flight chamber to support a user against the force of gravity. Conventionally, ingress/egress openings in the flight chamber or in an area adjacent to the flight chamber are provided with a single air lock door which is closed in substantially sealed, air tight condition while the flight chamber is in use and which is designed and intended to be opened only when the air flow in the flight chamber has been reduced. Thus, users entering or exiting from the flight chamber or an area adjacent to the flight chamber are usually required to do so only when the flight chamber is not in use.
With these conventional designs, the fan speed for the flight chamber, and thus the air flow in the flight chamber, is normally reduced when the air lock door is open to allow users to enter or exit the flight chamber or areas adjacent to the flight chamber. Then, after the air lock door has been closed and sealed, the fan speed is increased to provide the necessary air flow to support a user against the force of gravity.
This repeated reduction and increase in the fan speed to allow users to enter or exit the flight chamber or adjacent areas not only results in increased wear and tear on the fan and other components of the system, but results in significant downtime since the system must be at least partially shut down to allow the users to enter and exit through the opened air lock door.
Accordingly, there is a need in the art to provide an improved ingress/egress system by which users can enter or exit from the flight chamber or areas adjacent to the flight chamber continuously, without decreasing the fan speed or significantly altering the use of the flight chamber.